THE FLEA. 191 



to enable us to state with certainty whether he uses his 

 hind legs as weapons in his contests with other insects ; 

 but it is to be presumed that he does so, for why otherwise 

 should Nature have endowed him with so much power in 

 these limbs ? If the ordinary mode of progression of the 

 flea were, like that of the grasshopper, by a succession of 

 springs, the prodigious size of his hind legs would be ac- 

 countable ; but, upon the contrary, the flea is essentially a 

 runner, and the speed with which he can make his way 

 through the thick fur of a cat or the hair of a dog is 

 wonderful. It does not appear, indeed, that he ever does 

 take to jumping except when inclined to drive human beings 

 on the search for him into a state of frenzy. 



As it cannot be reasonably supposed that Nature gifted 

 the flea with such abnormal saltatory powers merely that 

 he should be a cause of bad language among the human 

 kind, some other explanation must be sought for. The 

 Darwinian theory, that living creatures develop by the 

 survival of the fittest such powers as may be most useful to 

 them, fails altogether here, unless it be supposed that the 

 flea's legs have developed only since he made his acquaint- 

 ance with man. In the earlier periods of his history, when 

 he lived in the hair or fur of animals, he could have had 

 no occasion whatever to jump. Unfortunately, the early 

 historians, in dealing with the flea, are silent as to the 

 length of his leaps, and we have, therefore, no means of 

 estimating the rate at which he has progressed , in this 

 accomplishment during the last two or three thousand years. 

 Yet, doubtless, he was present at the Siege of Troy, dwelt 

 in the tent of Achilles, and stirred Ulysses to occasional 

 wrath ; it would have been well, then, had Homer turned 



